Magnetic clusters in semiconductors

Collaboration:

Abstract

According to the necessity of ferromagnetic semiconductor materials for spintronics, the project is focused on the investigation of magnetic clusters embedded in semiconductors. The new aspects of the project are given by the investigation of the effect of magnetic nanoparticles on the charge carriers and of magnetic phenomena induced by implantation defects. The analysis is focused on high-resolution techniques using photon beams. These techniques will allow the clear identification of secondary phases as well as the element specific investigation of the electronic structure.

Figures

The presence of a ferromagnetic diluted magnetic semiconductor (DMS) based on ZnO can be confused with non-detectable metallic nanoparticles.

SQUID

Röntgendiffraktion

The zero-field cooled / field cooled magnetization vs. temperature dependence clearly shows freezing/defreezing effects of magnetic moments. The latter can be explained by the presence of superparamagnetic nanoparticles

Direct evidence for the existence of crystalline α-Fe nanoparticles is given by XRD. Note that only the high sensitive synchrotron XRD can detect these tiny particles while common lab XRD fails.

Non - systematic dependence of the magnetisation on the particle size of MnSi nanoparticles formed via Mn implantation into Si has been observed.

The nanoparticles MnSi1.7 show increase in size with increasing Mn fluence ((a) 1×1015 cm-2, (b) 1×1016 cm-2 and (c) 5×1016 cm-2. ). Only for the middle fluence, however, superparamagnetism can be observed.